The present invention relates to air ionizers and, more particularly, to an improved air ionizer which provides for enhanced performance.
Air ionizers are generally well known in the art and are employed for a variety of uses, one of which is reducing electrostatic discharge in connection with the manufacture of semiconductors and other products. Air ionizers generate large quantities of both positive and negative ions which are dispensed into the surrounding atmosphere to increase the conductivity of the air within a facility. As ions from the air ionizer flow through the air they are attracted to oppositely charged particles and surfaces causing neutralization of such particles and surfaces. The result is that the positive and negative ions in the ionized air create a static dissipative environment by making the air a carrier of beneficial charges which both dissipate unwanted charges once they occur and significantly limit the magnitude of possible charge generation.
There are several different types of electrically operated air ionizers, although, the fundamental technology employed for generating ions, known as corona discharge is generally the same in all such electrical air ionizers. Electrical ionizers generate air ions by intensifying an electrical field on an electrode having a sharp point until the electrical field overcomes the dielectric strength of the surrounding air. Negative corona occurs when free electrons flow from the electrode into the surrounding air. Positive corona results from the flow of electrons from the air molecules into the electrode. The resulting ion current strength is a function of the applied voltage, the sharpness and conductivity of the electrode, the humidity of the air, atmospheric pressure and other factors.
A typical electrical ionizer comprises a housing having an air inlet, a high voltage source, an electrode with a sharp point connected to the high voltage source for creating the corona discharge which generates the ions, an air outlet and a fan, blower or other air mover for causing air to flow in through the air inlet, past the electrode for picking up the ions and out through the air outlet to the surrounding environment.
While existing electrically operated air ionizers function well for their intended purpose, in some situations, undesirable components, such as noise ions, AC ionization ripple and the like are generated within the air ionizer and are released to the surrounding environment. In addition, in some applications, it is desirable to have the ability to control the output of an electrically operated air ionizer without controlling the high voltage which is applied to the electrode. The present invention comprises an improved air ionizer which provides for both filtering of noise ions, unwanted AC ionization ripple and other unwanted components and better controlling the air ionizer output balance.
Briefly stated, the present invention comprises an improvement in an air ionizer apparatus. The air ionizer apparatus comprises an air inlet, a high voltage source, an electrode electrically connected to the high voltage source for generating ions, an air outlet and an air mover for causing air to flow into the air ionizer through the air inlet, around the electrode and out of the air ionizer through the air outlet. The improvement comprises a foraminous filter comprising an electrically conductive material. The filter is electrically coupled to at least one of a voltage source and ground and is positioned over at least one of the air inlet, the air outlet and the electrode such that air flowing into the air inlet, air flowing out of the air outlet or air flowing past the electrode flows through the filter. In a preferred embodiment, the filter comprises a metal grid or screen.